Potential for FT4 on 6 Meters

The E_s (sporadic E) season is well underway. It peaks at the solstice, which is less than 3 weeks from now. Although the season is reasonably long it is less so for DXing, which requires multiple clouds and long path lengths. When it does occur the openings are usually fleeting.

Openings for any one signal are often too short for most stations to complete an FT8 QSO. Bigger stations -- power and antennas -- or those in excellent locations do better. There are in principle two factors to be overcome in achieving DX success on 6 meters E_s:

• Weak signals: The combination of multiple bounces and forward scatter keep DX signals in almost all cases quite weak, even for those with big antennas.
• Brief opportunity: For the same reasons each signal can be in and out in less than one minute, the minimum duration for an FT8 QSO.

In the first case the challenge can be overcome with more power and more antenna. Unfortunately that is not practical for most hams, especially when it comes to towers and and antennas. But if you can do it you will see a tremendous improvement in your results.

In the second case you can increase the window of opportunity with more power, a bigger antenna or both. However, for the majority the greater opportunity is with modes that allow for quicker QSOs. That way you can exploit the propagation peaks and not just their long heads and tails.

The diagram is copied from the article linked above since I believe it makes clear the QSO duration challenge. See the article for a description of the diagram.

Traditional modes are fast, but...

Although CW and SSB are faster than FT8 (and even the twice-as-fast FT4) you are rarely in the right place at the right time. I discussed this "discovery" problem in an article last summer.

It is a major reason why FT8 has been so successful on 6 meters that it reduced CW and SSB activity by at least 80% in just one E_s season. You can't argue with success. Well you can but arguing won't put DX QSOs in the log. It's the only reason I made the move to FT8. Trying CW in a recent opening saw me through only 3 QSOs, including one Caribbean station I have not heard on FT8. SSB activity was a little better.

TEP, tropospheric ducting and (we hope) F₂ benefit less from the speed of FT4. FT8 is fine but then so are CW and SSB for these propagation modes. When signals persist the comparison between digital and traditional modes is little different than for HF. To give you my take on this I will merely state that I do not use FT8 on HF.

Expectations

I am intrigued by FT4. As of its latest incarnation the time slots are half that of FT8 (7.5 seconds), promising QSOs in half the time. Indeed it may be even faster since there is the possibility of fewer message repeats due to QSB during a lengthy FT8 QSO.

Despite not having used FT4 and the few reports I've heard from those using it I am comfortable predicting that FT4 most likely will be a good fit for 6 meters. In particular to E_s DX openings.

• Loss of a few db of sensitivity is more than compensated for by speed
• Ability to squeeze more QSOs out of brief DX openings
• Favours the small station better than FT8; while this may seem surprising consider the ability to better exploit brief propagation peaks

I have not yet used FT4. I am content to wait for it to stabilize. This is scheduled for July. That leaves me with enough time to play with it at the tail end of this E_s season. Others are using the beta software on 6 meters at its proposed slot of 50.318 MHz.

But more than a choice of mode my main concern right now is propagation. DX opportunities have been slim lately on 6 meters despite a promising beginning in mid-May. DX has been worked though nothing new or of especial note.

I listen most days with WSJT-X monitoring 50.313 MHz while I go about other activities. Between 6 meters and chasing 3D2CR there is enough DXing to fill the gaps in my busy warm weather schedule.